Recently, mobile information terminal devices such as PDAs and tablet personal computers have become increasingly popular and widespread. For such a mobile information terminal device, it is difficult to provide a keyboard or a mouse as its input device in order to increase its handiness and to meet the demand for size and weight reduction. That is why many of those devices use a touchscreen panel (which is sometimes called simply a “touchscreen”), including transparent thin film electrodes, as its display section (such as an LCD panel) so as to allow the user to operate the panel with a stylus or his or her finger.
Although it is easy to operate the machine with fingers, the display section soon gets dirty so much as to decrease the visibility of the display section. What is worse, the dirty display section has bacteria and is not hygienic. For that reason, if such an information display device needs to be used in a medical facility such as a hospital, the display section thereof should be cleaned and disinfected on a regular basis.
However, as the touchscreen panel is a transparent sheet, the dirt can not be seen so easily that it is usually difficult for a general user to decide when to clean it. Also, even after he or she has cleaned the screen, he or she is often still not sure if the dirt, dust or fingerprints have been removed from the screen sufficiently.
In order to overcome these problems, Patent Document No. 1 proposes the following method.
Specifically, Patent Document No. 1 discloses a technique for switching to a cleaning mode automatically when the number of times the touchscreen panel has been touched with a finger, which is counted by a counting means, reaches a predetermined number.
In the cleaning mode, the entire screen of the display section is displayed in a single color and the wiped and cleaned part is detected and has that colors erased or its colors changed into another one, thereby letting the user know what parts have been wiped.